The research activity is aimed at studying the feasibility of a Geosynchronous SAR system for Atmosphere and Terrain observation (GEOSAT). Such system could be implemented as an additional payload on telecommunication satellites and would be the natural complement to well established Low Earth Orbiting SAR systems. The research will focus on both the design of the whole system (including orbits, sensor parameters, acquisition modes...) and the development of accurate and efficient techniques for the processing of the acquired data. An important research topic will be the study of the statistics of atmosphere and scene, which have critical impacts on Geosynchronous SAR systems performances. The research activity will then focus on the definition of the GEOSAT Ground Segment. In particular an accurate GEOSAT data simulator and a prototype processor will be defined and implemented. During the prototype processor implementation, parallelization techniques will be exploited in order to maximize the throughput. The designed Geosynchronous SAR system could be a good candidate for a future ESA Explorer mission.